1. Field of the Invention
This invention relates to a Ti-Al based lightweight-heat resisting material and, more particularly to the improvement in its oxidation resistance.
2. Description of the Prior Art
In recent years, high-speed reciprocating members such as an engine valve, a piston, a rocker arm and the like, or high-speed rotating members such as a turbine blade of a gas turbine or a jet engine, a turbo charger rotor and the like come to be required more and more to have lightness and heat resistance with the improvement of the engine into the high-powered and highly efficient type. According to the requirements, many studies and development of materials for such members have been done actively.
At the present time, Ni-based superalloys are used mainly as materials for said high-speed moving members, besides titanium alloys or ceramic materials are used, however said Ni-based superalloys and ceramic materials have a weakpoint in that they lack reliability as a material for said members because said Ni-based superalloys have a disadvantageous point that they are heavy in weight and said ceramic materials are inferior in the toughness.
Therefore, Ti-Al based materials mainly consisting of an intermetallic compound Ti-Al have been attracted interest lately. Said Ti-Al based materials are superior to the Ni-based superalloys in the lightness and also surpass the ceramic materials in the toughness, however the Ti-Al based materials have a weakpoint of being inferior in the oxidation resistance, accordingly the fact is that they have not been put into practical use as yet.